Application of P450 reporter gene system (RGS) in the analysis of sediments near pulp and paper mills

Cytochrome P4501A (CYP1A) induction in fish and other animals has been repo rted following exposure to pulp and paper mill effluent. Dioxins and furans as well as polycyclic aromatic hydrocarbons (PAH) are known inducers of CY P1A and have been found in sediments near pulp and paper mills. Retene (7-i sopropyl-1-methylphenanthrene), an alkyl-substituted phenanthrene, has been recently associated with effluent and found to induce CYP1A in fish. This study utilized an in vitro assay, P450 Reporter Gene System (RGS), to asses s the transcriptional activation of human CYP1A by retene after short (6 h) and long (16 h) exposures. Retene was as potent as benzo[ a] pyrene in ind ucing RGS, but was not as readily biotransformed by the cells. Extracts of sediments collected near a pulp and paper mill were analysed, and RGS-deriv ed toxic equivalencies (TEQ) were strongly correlated with Chemical TEQ ana lysis of dioxins and furans determined by EPA Method 8290 using high-resolu tion gas chromatography/mass spectrometry. RGS 6-h responses indicated the presence of PAH in the extracts, which was confirmed by GC/MS analysis. Ret ene was detected at considerably higher concentrations than other PAH. Thes e data support the use of the RGS assay to detect the presence of CYP1A-ind ucing compounds, including retene as well as dioxins and furans, in sedimen ts near pulp mills.